Method of TDM in-device coexistence interference avoidance

ABSTRACT

A method of TDM in-device coexistence (IDC) interference avoidance is proposed. In a wireless communication device, a first radio module is co-located with a second radio module in the same device platform. The first radio module obtains traffic and scheduling information of the second radio module. The first radio module then determines a desired TDM pattern based on the traffic and scheduling information to prevent IDC interference with the second radio module. The first radio module also transmits TDM coexistence pattern information based on the desired TDM pattern to a base station. In one embodiment, the TDM coexistence pattern information comprises a recommended TDM pattern periodicity and a scheduling period to maximize IDC efficiency subject to limited level of IDC interference possibility. In one specific example, the TDM coexistence pattern information comprises a set of discontinuous reception (DRX) configuration parameters defined in long-term evolution (LTE) 3GPP standards.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 from U.S.Provisional Application No. 61/388,687, entitled “Method of TDMIn-Device Coexistence Interference Avoidance,” filed on Oct. 1, 2010,the subject matter of which is incorporated herein by reference.

TECHNICAL FIELD

The disclosed embodiments relate generally to wireless networkcommunications, and, more particularly, to TDM solutions for in-devicecoexistence (IDC) interference avoidance.

BACKGROUND

Ubiquitous network access has been almost realized today. From networkinfrastructure point of view, different networks belong to differentlayers (e.g., distribution layer, cellular layer, hot spot layer,personal network layer, and fixed/wired layer) that provide differentlevels of coverage and connectivity to users. Because the coverage of aspecific network may not be available everywhere, and because differentnetworks may be optimized for different services, it is thus desirablethat user devices support multiple radio access networks on the samedevice platform. As the demand for wireless communication continues toincrease, wireless communication devices such as cellular telephones,personal digital assistants (PDAs), smart handheld devices, laptopcomputers, tablet computers, etc., are increasingly being equipped withmultiple radio transceivers. A multiple radio terminal (MRT) maysimultaneously include a Long-Term Evolution (LTE) or LTE-Advanced(LTE-A) radio, a Wireless Local Area Network (WLAN, e.g., WiFi) accessradio, a Bluetooth (BT) radio, and a Global Navigation Satellite System(GNSS) radio.

Due to spectrum regulation, different technologies may operate inoverlapping or adjacent radio spectrums. For example, LTE/LTE-A TDD modeoften operates at 2.3-2.4 GHz, WiFi often operates at 2.400-2.483.5 GHz,and BT often operates at 2.402-2.480 GHz. Simultaneous operation ofmultiple radios co-located on the same physical device, therefore, cansuffer significant degradation including significant coexistenceinterference between them because of the overlapping or adjacent radiospectrums. Due to physical proximity and radio power leakage, when thetransmission of signal for a first radio transceiver overlaps with thereception of signal for a second radio transceiver in time domain, thesecond radio transceiver reception can suffer due to interference fromthe first radio transceiver transmission. Likewise, signal transmissionof the second radio transceiver can interfere with signal reception ofthe first radio transceiver.

FIG. 1 (Prior Art) is a diagram that illustrates interference between anLTE transceiver and a co-located WiFi/BT transceiver and GNSS receiver.In the example of FIG. 1, user equipment (UE) 10 is an MRT comprising anLTE transceiver 11, a GNSS receiver 12, and a BT/WiFi transceiver 13co-located on the same device platform. LTE transceiver 11 comprises anLTE baseband module and an LTE RF module coupled to an antenna #1. GNSSreceiver 12 comprises a GNSS baseband module and a GNSS RF modulecoupled to antenna #2. BT/WiFi transceiver 13 comprises a BT/WiFibaseband module and a BT/WiFi RF module coupled to antenna #3. When LTEtransceiver 11 transmits radio signals, both GNSS receiver 12 andBT/WiFi transceiver 13 may suffer coexistence interference from LTE.Similarly, when BT/WiFi transceiver 13 transmits radio signals, bothGNSS receiver 12 and LTE transceiver 11 may suffer coexistenceinterference from BT/WiFi. How UE10 can simultaneously communicate withmultiple networks through different transceivers and avoid/reducecoexistence interference is a challenging problem.

FIG. 2 (Prior Art) is a diagram that illustrates the signal power ofradio signals from two co-located RF transceivers. In the example ofFIG. 2, transceiver A and transceiver B are co-located in the samedevice platform (i.e., in-device). The transmit (TX) signal bytransceiver A (e.g., WiFi TX in ISM CH1) is very close to the receive(RX) signal (e.g., LTE RX in Band 40) for transceiver B in frequencydomain. The out of band (OOB) emission and spurious emission resulted byimperfect TX filter and RF design of transceiver A may be unacceptableto transceiver B. For example, the TX signal power level by transceiverA may be still higher (e.g. 60 dB higher before filtering) than RXsignal power level for transceiver B even after the filtering (e.g.,after 50 dB suppression).

In addition to imperfect TX filter and RF design, imperfect RX filterand RF design may also cause unacceptable in-device coexistenceinterference. For example, some RF components may be saturated due totransmit power from another in-device transceiver but cannot becompletely filtered out, which results in low noise amplifier (LNA)saturation and cause analog to digital converter (ADC) to workincorrectly. Such problem actually exists regardless of how much thefrequency separation between the TX channel and the RX channel is. Thisis because certain level of TX power (e.g., from a harmonic TX signal)may be coupled into the RX RF frontend and saturate its LNA. If thereceiver design does not consider such coexistence interference, the LNAmay not be adapted at all and keep saturated until the coexistenceinterference be removed (e.g. by turning off the interference source).

Various in-device coexistence (IDC) interference avoidance solutionshave been proposed. For example, an UE may request network assistance toprevent IDC interference via frequency division multiplexing (FDM), timedivision multiplexing (TDM), and/or power management principles. Themajor concerns on TDM solutions are how much complexity to eNBscheduler, how UE can help eNB generate proper gaps, how UE can utilizethe gaps generated by eNB, how much performance improvement can beachieved, and how much impact to the existing LTE/LTE-A standardspecifications. Possible TDM solutions include DRX/DTX, measurement,SPS, MBMS, scheduling via PDCCH, and a new protocol. It is desirable tofind a TDM solution that can generate the TX/RX gaps with moreflexibility and less impact to existing design and implementation.

SUMMARY

A method of TDM in-device coexistence (IDC) interference avoidance isproposed. In a wireless communication device, a first radio module isco-located with a second radio module in the same device platform. Thefirst radio module obtains traffic and scheduling information of thesecond radio module. The first radio module then determines a desiredTDM pattern based on the traffic and scheduling information to preventIDC interference with the second radio module. The first radio modulealso transmits TDM coexistence pattern information based on the desiredTDM pattern to a base station (eNB). In one embodiment, the TDMcoexistence pattern information comprises a recommended TDM patternperiodicity and a scheduling period to maximize IDC efficiency subjectto limited level of IDC interference possibility.

In one specific example, the TDM coexistence pattern informationcomprises a set of discontinuous reception (DRX) configurationparameters defined in 3GPP long-term evolution (LTE) standards. If thesecond radio module is a WiFi radio having WiFi beacon signalperiodicity of 102.4 ms, then the eNB configures DRX operation with alongDRX-Cycle equal to 128 ms or 64 ms, and the OnDurationTimer is smallenough such that collision probability between the first and the secondradio modules is lower than a threshold value. Upon receiving an IDCinterference indication, the eNB may restrict some flexible extension ofan ON duration within each DRX cycle to further reduce collisionprobability.

Other embodiments and advantages are described in the detaileddescription below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like numerals indicate like components,illustrate embodiments of the invention.

FIG. 1 (Prior Art) is a diagram that illustrates interference between anLTE transceiver and a co-located WiFi/BT transceiver and GNSS receiver.

FIG. 2 (Prior Art) is a diagram that illustrates the signal power ofradio signals from two co-located RF transceivers in a same deviceplatform.

FIG. 3 illustrates a user equipment having multiple radio transceiversin a wireless communication system in accordance with one novel aspect.

FIG. 4 is a simplified block diagram of a wireless device having acentral control entity.

FIG. 5 illustrates one embodiment of TDM solution for IDC interferenceavoidance in accordance with one novel aspect.

FIG. 6 illustrates a basic DRX cycle and corresponding DRX configurationparameters.

FIG. 7 illustrates examples of LTE DRX traffic patterns with differentDRX configuration parameters.

FIG. 8 illustrates traffic pattern and scheduling parameters of an LTEsystem and an ISM target system for coexistence problems.

FIG. 9 illustrates examples of various LTE DRX configurations thatcoexist with WiFi Beacon.

FIG. 10 is a simulation diagram of Probability to Collide vs.Coexistence Efficiency under different DRX configuration parameters.

FIG. 11 illustrates possible modifications on existing DRX protocol.

FIG. 12 is a flow chart of a method of TDM solution for IDC interferenceavoidance from UE perspective in accordance with one novel aspect.

FIG. 13 is a flow chart of a method of TDM solution for IDC interferenceavoidance from eNB perspective in accordance with one novel aspect.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 3 illustrates a user equipment UE31 having multiple radiotransceivers in a wireless communication system 30 in accordance withone novel aspect. Wireless communication system 30 comprises a userequipment UE31, a serving base station (e.g., evolved node-B) eNB32, aWiFi access point WiFi AP33, a Bluetooth device BT34, and a globalpositioning system satellite device GPS35. Wireless communication system30 provides various network access services for UE31 via different radioaccess technologies. For example, eNB32 provides OFDMA-based cellularradio network (e.g., a 3GPP Long-Term Evolution (LTE) or LTE-Advanced(LTE-A) system) access, WiFi AP33 provides local coverage in WirelessLocal Area Network (WLAN) access, BT34 provides short-range personalnetwork communication, and GPS35 provides global access as part of aGlobal Navigation Satellite System (GNSS). To access various radionetworks, UE31 is a multi-radio terminal (MRT) that is equipped withmultiple radios coexisted/co-located in the same device platform (i.e.,in-device).

Due to spectrum regulation, different radio access technologies mayoperate in overlapping or adjacent radio spectrums. As illustrated inFIG. 3, UE31 communicates radio signal 36 with eNB32, radio signal 37with WiFi AP33, radio signal 38 with BT34, and receives radio signal 39from GPS35. Radio signal 36 belongs to 3GPP Band 40, radio signal 37belongs to one of the WiFi channels, and radio signal 38 belongs to oneof the seventy-nine Bluetooth channels. The frequencies of all thoseradio signals fall within a range from 2.3 GHz to 2.5 GHz, which mayresult in significant in-device coexistence (IDC) interference to eachother. The problem is more severe around the 2.4 GHz ISM (TheIndustrial, Scientific and Medical) radio frequency band. Various IDCinterference avoidance solutions have been proposed. In one novelaspect, UE31 triggers specific Time Division Multiplexing (TDM)-basedsolutions for IDC interference avoidance. The TDM-based solutionsrequire internal device coordination, such as a central control entitythat communicates with the multiple radios within UE31.

FIG. 4 is a simplified block diagram of a wireless device 41 having acentral control entity to facilitate TDM solutions for IDC interferenceavoidance. Wireless device 41 comprises memory 43, a processor 44, acentral control entity 45, an LTE transceiver 46, a GPS receiver 47, aWiFi transceiver 48, a Bluetooth transceiver 49, and bus 101. In theexample of FIG. 4, central control entity 45 is a logical entityphysically implemented within the LTE transceiver 46. Alternatively,central control entity 45 can be a logical entity implemented within aprocessor that is physically located within WiFi transceiver 48, BTtransceiver 49, or processor 44 that is also used for device applicationprocessing for device 41. Central control entity 45 is connected tovarious transceivers within device 41, and communicates with the varioustransceivers via bus 101.

For example, WiFi transceiver 48 transmits WiFi signal informationand/or WiFi traffic and scheduling information to central control entity45 (e.g., depicted by a dotted line 102). Based on the received WiFiinformation, central control entity 45 determines control informationand transmits the control information to LTE transceiver 46 (e.g.,depicted by a dotted line 103). In one embodiment, LTE transceiver 46learns the WiFi activity through control entity 45 and detects IDCinterference between LTE and WiFi. LTE transceiver 46 triggers TDMsolution for IDC interference avoidance and communicates with itsserving base station eNB42 to indicate a recommended TDM coexistencepattern (e.g., depicted by a dotted line 104). Based on the TDMcoexistence pattern information, eNB42 is able to determine the bestsuitable TDM solution for device 41 to prevent IDC interference betweenLTE and WiFi effectively.

FIG. 5 illustrates one embodiment of TDM solution for IDC interferenceavoidance in wireless network 50 in accordance with one novel aspect.Wireless network 50 comprises an eNB51, a WiFi AP52, and an UE53. UE53comprises an LTE radio module (e.g., transceiver) 54, an ISM BT/WiFiradio module (e.g., transceiver) 55, and a central control entity 56. Inone novel aspect, control entity 56 learns ISM Tx/Rx activity fromBT/WiFi transceiver 55 (step 1) and informs the ISM Tx/Rx timinginformation to LTE transceiver 54 (step 2). Based on the ISM Tx/Rxtiming information, LTE radio module 54 triggers IDC interferenceavoidance mechanism and indicates a recommended coexistence pattern toeNB51 (step 3). In addition, LTE radio module 54 may also reports ISMtraffic and scheduling information to eNB51 to further assist IDCconfiguration. Based on the received coexistence pattern information,eNB51 determines the best suitable TDM solution for UE53 to prevent IDCinterference (step 4). In one specific embodiment, eNB51 configures UE53with discontinuous reception (DRX) operation that controls the ON/OFFcycle and Tx/Rx activity of UE53 by configuring a set of DRX parameters.

FIG. 6 illustrates a basic DRX cycle and corresponding DRX configurationparameters. A basic DRX cycle consists of an ON Duration (e.g.,sometimes referred to as a scheduling period) and an Opportunity for DRXDuration. In RRC_CONNECTED mode, if DRX operation is configured on a UE,then the UE is allowed to monitor the Physical Downlink Control Channel(PDCCH) discontinuously using the DRX operation. In general, the UEshall monitor the PDCCH during the ON Duration, and may stop monitoringthe PDCCH during the Opportunity for DRX Duration. While the DRX cyclelength and the On Duration are fixed under a certain DRX configuration,the Active Time (i.e., the duration when the UE is active for possibleRX and TX) is extendable from the ON Duration, which may happen duringthe Opportunity for DRX Duration period. A DRX cycle is controlled viaradio resource control (RRC) layer messaging by configuring onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer, thelongDRX-Cycle, the value of the drxStartOffset, and optionally thedrxShortCycleTimer and shortDRX-Cycle.

When a DRX cycle is configured, the Active Time in each DRX cyclevaries, depending on the configured DRX parameters. The Active Time isextendable from the ON Duration based on the following four conditions.First, the Active Time includes the time while on DurationTimer ordrx-InactivityTimer or macContentionResolutionTimer is running. Second,the Active Timer includes the time while a Scheduling Request is sent onPUCCH and the Scheduling Request is pending. Third, the Active Timeincludes the time while an uplink grant for a pending HARQretransmission can occur and there is data in the corresponding HARQbuffer. Fourth, the Active Time includes the time while a PDCCHindicating a new transmission addressed to the C-RNTI of the UE has notbeen received after successful reception of a Random Access Response forthe preamble not selected by the UE. If any of the four conditions ismet, the Active Time is extended from the ON Duration.

FIG. 7 illustrates examples of LTE DRX traffic patterns with differentDRX configuration parameters. In the example of FIG. 7, all three DRXtraffic patterns have a longDRX-Cycle equal to 128 ms. The on Durationparameter, however, is different in different DRX configuration. UnderDRX CONFIG#1, traffic pattern (7A) has an on DurationTimer equal to 100ms, with DRX-InactivityTimer set to 10 ms. Under DRX CONFIG#2, trafficpattern (7B) has an on DurationTimer equal to 80 ms, withDrx-InactivityTimer set to 20 ms. Under DRX CONFIG#3, traffic pattern(7C) has an on DurationTimer equal to 60 ms, with DRX-InactivityTimerset to 40 ms. It can be seen that even under the same DRX duty cycle,the UE may have different ON Duration with different on DurationTimer.Furthermore, the DRX-InactivityTimer can keep the UE stay in Active Timeand equivalently extend the ON Duration (i.e., which may happen duringthe Opportunity for DRX Duration period). Therefore, DRX protocolsupports good flexibility on configuration, and different parametervalues can lead to various gap patterns in time domain. As a result, DRXprotocol may function as a good TDM solution for IDC interferenceavoidance.

The principle of TDM solution for coexistence system is for eNB to havemaximum scheduling flexibility while avoiding coexistence interferenceby reducing time overlap between LTE and ISM traffic. Therefore, in oneexample, under TDM solution, the general objective function forcoexistence systems is:Maximize {Coexistence Efficiency} subject to {P _(C) <P _(C) _(—)_(REQ)}  (1)where

-   -   Coexistence Efficiency (CE)=(Duration that eNB can grant        resources for LTE TX/RX)/(Observation Time)    -   Probability to Collide (P_(C))=[Duration that eNB can grant        resources for LTE TX/RX while (“ISM transceiver can RX/TX” or        “GLASS receiver can RX”)+extension factor]/(Observation Time)    -   P_(C) _(—) _(REQ)=the required threshold value of P_(C).

Coexistence efficiency (CE) is associated with eNB schedulingflexibility. Higher CE means eNB have more time to possibly scheduledata transmission or reception to UE. Probability to collide (P_(C))means the level of possibility that coexistence interference may happen.The real collision probability further considers the probability thateNB schedules DL/UL grant and the probability that ISM system schedulesUL/DL grant or the probability that GNSS system performs DL reception.Because the LTE sub-frame boundary may not be 100% aligned with ISM orGNSS system, additional probability to collide may be increased due toconverting the problem into an integer-programming problem. In addition,the extension factor is introduced in this example to capture thevariation of the DRX boundary condition, which is a positive value andthus may further increase the probability to collide.

From LTE perspective, the general objective for coexistence systems isto maximize eNB scheduling flexibility (e.g., a function of CE) whilelimit coexistence interference probability (e.g., a function of P_(C))to be less than a required threshold P_(C) _(—) _(REQ). P_(C) _(—)_(REQ) may be defined based on the traffic pattern and QoS requirementsassociated with ISM transceiver or GNSS receiver. In one example, P_(C)_(—) _(REQ) may be 10% for voice traffic based on affordable QoSdegradation allowed by user. In another example, P_(C) _(—) _(REQ) maybe 0% for critical system information to be exchanged by ISM transceiver(e.g., WiFi beacon or BT initial connection setup).

FIG. 8 illustrates traffic pattern and scheduling parameters of an LTEsystem and an ISM target system for coexistence problems. Assume thatperiodic radio signals are transmitted in the ISM target system (e.g.,WiFi Beacon), and that DRX operation is enabled in the LTE system. Thefollowing traffic scheduling parameters are illustrated in FIG. 8:

-   -   T_(target): Periodicity of the signal transmitted in target        system    -   t_(transmit) (m): Transmission time over m-th transmission    -   T_(onDuration): on DurationTimer configured by eNB    -   T_(longDRX-Cycle): longDRX-Cycle configured by eNB    -   t_(DRX-Inactivity) (n): Extended on Duration time by        DRX-Inactivity timer in n-th DRX cycle    -   T_(offset): time offset between 1^(st) DRX cycle start point and        the incoming signal in target system

Based on the above-illustrated traffic scheduling parameters, bothcoexistence efficiency (CE) and probability to collide (P_(C)) can becalculated. As a result, the best suitable DRX configuration parameterscan be determined by the eNB to satisfy the general objective offunction (1), under the assumption that the eNB knows the exact signaltransmission timing and periodicity of the target system.

It is, however, a difficult task to achieve the general objectivefunction (1). First, the eNB typically does not know the trafficscheduling parameters of the target system and thus will not be able todetermine the best DRX configuration parameters. Second, the trafficscheduling parameters of the target system may be complicated andunpredictable. To address the first issue, the eNB needs to rely on theUE with in-device coordination capability to recommend preferred DRXconfiguration. Referring back to FIG. 5, for example, eNB51 relies onthe coexistence pattern information sent from LTE radio module 54 todetermine the preferred DRX configuration parameters. To address thesecond issue, simplified periodic traffic patterns such as the WiFibeacon signal may be used as a starting point to investigate potentialDRX-based solutions for coexistence problems.

FIG. 9 illustrates examples of various LTE DRX configurations thatcoexist with WiFi Beacon. In the example of FIG. 9, the WiFi Beacontraffic pattern (9A) has a signal periodicity of 102.4 ms, and the WiFibeacon signal transmission duration is less than 3 ms in general. ForLTE DRX CONFIG#1, traffic pattern (9B) has a longDRX-Cycle of 128 ms,and an on Duration=100 ms. For LTE DRX CONFIG#2, traffic pattern (10C)has a longDRX-Cycle of 128 ms, and an on Duration=80 ms. For LTE DRXCONFIG#3, traffic pattern (10D) has a longDRX-Cycle of 128 ms, and an onDuration=60 ms. Assume that the first LTE DRX cycle boundary has beenaligned with the WiFi beacon. If t_(WiFi) _(—) _(Rx) denotes the time toreceive WiFi beacons, and t_(LTE) _(—) _(Tx) denotes the time to havepossible LTE UL TX, and x denotes the longDRX-Cycle, then we have:Coexistence Efficiency CE=Sum(t _(LTE) _(—) _(Tx))/[102,4,x]  (2)Probability to Collide P _(C)=Probability(t _(WiFi) _(—) _(Rx) =t _(LTE)_(—) _(Tx)  (3)

To satisfy the general objective as defined by function (1), thecoexistence efficiency (CE) will be increased if t_(LTE) _(—) _(Tx) isincreased. On the other hand, the probability to collide P_(C) that theWiFi beacon will collide with LTE TX will also be increased if t_(LTE)_(—) _(Tx) is increased. Although changing t_(LTE) _(—) _(Tx) may resultin contradictory performance, it is still possible to find the besttradeoff. As illustrated in FIG. 9, when the on Duration is decreased to60 ms, there is less collision between the WiFi beacon and possible LTEtraffic. Therefore, it is possible to determine which DRX configurationparameters can provide the best solution to avoid IDC interferencebetween LTE and WiFi beacon.

FIG. 10 is a simulation diagram of Probability to Collide vs.Coexistence Efficiency under different DRX configuration parameters. Thesimulation considers that the LTE eNB can configure DRX parameters forUE to perform coexistence interference avoidance with WiFi beacon forin-device WiFi transceiver. The WiFi beacon periodicity is 102.4 ms, andthe WiFi beacon transmission time is 1-3 ms. The DRX parameters to becontrolled are the longDRX-Cycle and the on DurationTimer. It is assumedthat the drx-InactivityTimer=1 ms, and no grant scheduled by eNB in thelast subframe of the on Duration to reduce simulation complexity. At thesystem level, it is further assumed that the eNB knows WiFi beacon isthe subject for coexistence, and the eNB knows the WiFi beacontransmission timing and periodicity.

From the simulation result in FIG. 10, it can be seen that good tradeoffbetween “probability to collide” and “coexistence efficiency” may beachieved by proper DRX configuration. More specifically, the DRXpatterns with longDRX-Cycle=128 ms or 64 ms can lead to the bestperformance tradeoff. For example, if longDRX-Cycle=128, when onDurationTimer is small, e.g., when coexistence efficiency is less than0.17, then the probability to collide is almost zero. Therefore,DRX-based solution is a feasible TDM solution for in-device coexistenceinterference avoidance.

In one advantageous aspect, the eNB may restrict flexible extension ofthe ON duration to reduce collision probability. Although DRX protocolsupports extendable ON Duration (e.g., the four conditions describedabove with respect to FIG. 6), such extendibility may increase collisionprobability. This is because the in-device WiFi radio may put alltraffic over the “Opportunity for DRX Duration” period to avoid the “ONDuration”, serious collision may happen if the eNB flexibly extends theON Duration based on those four conditions. It is thus proposed that atleast one of the conditions is disabled (e.g., disable thedrx-InactivityTimer) to restrict eNB flexibility and provide in-deviceradio more reliable protection. It should be noted that thosecondition(s) would only be disabled when UE indicates it has coexistenceinterference problem and will not be applied under normal scenario. Inone example, a UE transmits an IDC interference indicator to the eNBwhen IDC interference is detected and IDC interference avoidancemechanism is triggered. Upon receiving the IDC interference indication,the eNB disables some of the conditions to restrict the flexibleextension of the ON Duration. In another example, the UE transmits anindicator to the eNB to restrict the flexible extension of the DRX ONDuration once the UE detects IDC interference.

Other possible TDM solutions for IDC interference avoidance may includeSemi-Persistent Scheduling (SPS), measurement gap, MBMS subframe,scheduling via PDCCH, and a new protocol. As compared to thosesolutions, DRX is the most promising solution because it is one of theexisting protocols available in Rel-8/9 specification and is applicablefor both RRC_Connected mode and RRC_Idel mode. Multiple DRXconfiguration parameter vales can lead to various gap patterns, tooptimize coexistence efficiency and reduce probability to collide. Inaddition, if some modifications are allowed, the DRX is still the mostpromising solution because more parameters or additional values ofexisting parameters may be considered for higher efficiency.

FIG. 11 illustrates possible modifications on existing DRX protocol.Various traffic patterns can be generated by jointly utilizinglongDRX-CycleStartOffset, on DurationTimer, drx-InactivityTimer, andshortDRX-Cycle to configure gap pattern for coexistence. In addition,drx-InactivityTimer may help to further improve coexistence efficiency.In the example of FIG. 11, DRX traffic pattern (11A) is based onlongDRX-CycleStartOffset and drx-InactivityTimer, DRX traffic pattern(11B) is based on shortDRX-Cycle, and DRX traffic pattern (11C) is basedon based on longDRX-CycleStartOffset, drx-InactivityTimer, andshortDRX-Cycle.

FIG. 12 is a flow chart of a method of TDM solution for IDC interferenceavoidance from UE perspective in accordance with one novel aspect. A UEcomprises a first radio module co-located with a second radio module inthe same device platform. In step 1201, the first radio module obtainstraffic or scheduling information of the second radio module. In step1202, the first radio module determines a desired TDM pattern based onthe traffic and scheduling information to mitigate IDC interference. Instep 1203, the first radio module detects IDC interference based oninterference measurement result and triggers interference avoidancemechanism. In step 1204, the first radio module transmits coexistencepattern information based on the desired TDM patter to a base stationwhen IDC interference avoidance mechanism is triggered. The coexistencepattern information may comprises a recommended TDM pattern periodicityand a scheduling period to maximize IDC efficiency subject to limitedlevel of IDC interference possibility.

FIG. 13 is a flow chart of a method of TDM solution for IDC interferenceavoidance from eNB perspective in accordance with one novel aspect. Instep 1301, the eNB receives coexistence pattern information from an LTEradio module co-located with a second radio module in a same deviceplatform. In step 1302, the eNB determines a set of DRX configurationparameters for the LTE radio based on the received coexistence patterninformation to mitigate IDC interference. In step 1303, the eNB restrictflexible extension of the ON Duration within each DRX cycle to furtherreduce collision probability once the eNB receives an IDC interferenceindication.

Although the present invention has been described in connection withcertain specific embodiments for instructional purposes, the presentinvention is not limited thereto. For example, although an LTE/LTE-A orWiMAX mobile communication system is exemplified to describe the presentinvention, the present invention can be similarly applied to othermobile communication systems, such as Time Division Synchronous Access(TD-SCDMA) systems. Accordingly, various modifications, adaptations, andcombinations of various features of the described embodiments can bepracticed without departing from the scope of the invention as set forthin the claims.

What is claimed is:
 1. A method comprising: obtaining, by a first radiomodule, traffic or scheduling information of a second radio moduleco-located with the first radio module in a wireless communicationdevice; determining a desired time-division multiplexing (TDM) patternfor the first radio module based on the traffic or schedulinginformation to mitigate in-device coexistence (IDC) interference withthe second radio module; and transmitting coexistence patterninformation based on the desired TDM pattern to a base station, whereinthe coexistence pattern information comprises a set of recommendeddiscontinuous reception (DRX) configuration parameters defined inlong-term evolution (LTE) 3GPP standards and a time offset between afirst DRX cycle start point and an incoming signal of the second radiomodule.
 2. The method of claim 1, wherein the coexistence patterninformation comprises a recommended TDM pattern periodicity and ascheduling period.
 3. The method of claim 1, wherein the set of DRXconfiguration parameters comprises an onDurationTimer, a DRX cycle, aDRX-Inactivity timer for on Duration extension.
 4. The method of 3,wherein a long DRX-Cycle is 128 ms or 64 ms, and wherein the secondradio module is a WiFi radio module having WiFi beacon signalperiodicity of 102.4 ms or multiple of 102.4 ms.
 5. The method of claim3, wherein the onDurationTimer is small enough such that collisionprobability between the first and the second radio modules is lower thana threshold value.
 6. The method of claim 3, further comprising:transmitting an IDC interference indicator to the base station such thatflexible extension for an ON duration in each DRX cycle is restricted toreduce collision probability between the first and the second radiomodules.
 7. The method of claim 1, further comprising: triggering an IDCinterference mitigation mechanism based on an IDC interferencemeasurement result, wherein the coexistence pattern information istransmitted to the base station when the IDC interference mitigationmechanism is triggered.
 8. A wireless communication device, comprising:a first radio module that obtains traffic or scheduling information of asecond radio module co-located with the first radio module; a controlentity that determines a desired time-division multiplexing (TDM)pattern for the first radio module based on the traffic or schedulinginformation to mitigate in-device coexistence (IDC) interference withthe second radio module; and a transmitter that transmits coexistencepattern information based on the desired TDM pattern to a base station,wherein the coexistence pattern information comprises a set ofrecommended discontinuous reception (DRX) configuration parametersdefined in long-term evolution (LTE) 3GPP standards and a time offsetbetween a first DRX cycle start point and an incoming signal of thesecond radio module.
 9. The device of claim 8, wherein the coexistencepattern information comprises a recommended TDM pattern periodicity anda scheduling period.
 10. The device of claim 8, wherein the set of DRXconfiguration parameters comprises an onDurationTimer, a DRX cycle, aDRX-Inactivity timer for on Duration extension.
 11. The device of claim10, wherein a long DRX-Cycle is 128 ms or 64 ms, and wherein the secondradio module is a WiFi radio module having WiFi beacon signalperiodicity of 102.4 ms or multiple of 102.4 ms.
 12. The device of claim10, wherein the onDurationTimer is small enough such that collisionprobability between the first and the second radio modules is lower thana threshold value.
 13. The device of claim 10, wherein the devicetransmits an IDC interference indicator to the base station such thatflexible extension for an ON duration in each DRX cycle is restricted toreduce collision probability between the first and the second radiomodules.
 14. The device of claim 8, wherein the device triggers an IDCinterference mitigation mechanism based on an IDC interferencemeasurement result, wherein the coexistence pattern information istransmitted to the base station when the IDC interference mitigationmechanism is triggered.
 15. A method comprising: receiving time-divisionmultiplexing (TDM) coexistence pattern information from a first LTEradio module in an long-term evolution (LTE) 3GPP wireless system,wherein the first LTE radio module and a second radio module areco-located in a same device platform, and wherein the coexistencepattern information comprises a set of recommended discontinuousreception (DRX) configuration parameters defined in long-term evolution(LTE) 3GPP standards and a time offset between a first DRX cycle startpoint and an incoming signal of the second radio module; and determininga set of discontinuous reception (DRX) configuration parameters for thefirst radio module based on the TDM coexistence pattern information tomitigate in-device coexistence (IDC) interference between the first LTEradio module and the second radio module.
 16. The method of claim 15,wherein the coexistence pattern information comprises a recommended TDMpattern periodicity and a scheduling period.
 17. The method of claim 15,wherein the set of DRX configuration parameters comprises anonDurationTimer, a DRX cycle, a DRX-Inactivity timer for onDurationextension.
 18. The method of 17, wherein a longDRX-Cycle is configuredto be 128 ms or 64 ms, and wherein the second radio module is a WiFiradio module having WiFi beacon signal periodicity of 102.4 ms ormultiple of 102.4 ms.
 19. The method of claim 17, wherein theonDurationTimer is configured to be small enough such that collisionprobability between the first and the second radio modules is lower thana threshold value.
 20. The method of claim 17, further comprising:receiving an IDC interference indication; and restricting flexibleextension of an ON duration within each DRX cycle to reduce collisionprobability between the first and the second radio modules.